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M.J.
Winter

(3D

DATAMOST

Atari 400/800/1200

$9. 95

mbui er

Computer
Playground

On the Atari

M.J. Winter, Ph.D.
Professor of Mathematics
Michigan State University

Illustrated by
Martin Cannon

Edatamost

8943 Fullbright Avenue

Chatsworth, CA 91 31 1 -2750

[213)709-1202

U DATAMOST

ISBN 0-B81 90-1 90-3

This manual is published and copyrighted by DATAMOST INC. Copying, duplicating, selling
or otherwise distributing this product is hereby expressly forbidden except by prior written con-
sent of DATAMOST INC.

The word ATARI and the Atari logo are registered trademarks of Atari Incorporated.

Atari Incorporated was not in any way involved in the writing or other preparation of this book,
nor were the facts presented here reviewed for accuracy by that company. Use of the term Atari
should not in any way be construed to represent any endorsement, official or otherwise, by
Atari Incorporated.

Acknowledgements

My thanks go to all those who encouraged me to write
something for younger children. Special appreciation is due to:

Dave Gordon and his very creative and supportive staff at
DATAMOST.

My fellow instructors at the MSU summer computer camps: Ed
Carlson, John Forsythe and Mark Lardie. Double thanks to Ed
with whom I wrote materials for the camp, and who encouraged
this project.

The children in the first classes - especially Amy, Linda, Harriet,
Claire, Ida, Elizabeth, Beth, Susie, Leah, Jason, Courtney,
Jessica, Erin and Jon.

All the teachers who've responded to my articles and programs,
describing the enthusiasm of their students.

My family, who not only live with my three computers in the
kitchen, but who liberally gave me suggestions and
encouragement.

The 6-year old, now 8, who started this project off when she
complained:

I don't want to just play games.
Show me how to make the computer DO something.

THE PROBLEMS

1 . Season's Greetings

2. Take a Number, Please

3. Mistakes

4. Initials

5. Where Now?

6. Wallpaper

7. Letter to Santa

8. Cursor Controls

9. Pausing for Breath

10. Rockets

11. Counting

12. Touch Your Toes Ten Times

13. Movers

14. The Worm

15. More Counting

16. Testing with IF. . . THEN

17. Goldilocks

18. Animal Guess

19. Little Indians

20. Nursery Rhyme

21. Blinking Lizards

22. Screen Colors

23. PEEKaboo

24. Funnybones and Sore Toes

25. Quiz Time

26. Pieces of Words

27. Rhyming Game

28. Word Puzzle

29. Doing Math

30. Math Quiz

31. Times Tables

32. Days and Nights

33. Sounding Off

34. Countdown

35. Think of a Number

36. Two Dice

37. Get Out of Jail

38. Number Guess

39. Answer Machine

40. Sound and Light Show

Introduction

This book is for the child who wants to make the computer "do"
something. It is based on the perception that such a child is
probably not thinking of evaluating arithmetic expressions, but
rather of making the computer respond to his/her directions. A
child who knows some BASIC will be able to "talk" to the
computer and control its actions.

The BASIC taught in this book will enable children to make the
computer "do" things that interest them. The method of
presentation is that of "conversational BASIC": each idea is
taught by the combination of an interesting format and lots of
repetition.

The book is intended for the child in grades 2.5—7 whose family
has an ATARI computer, or for children who have access to a
classroom computer. While the programs presented are
specifically designed to work on the ATARI, this is not a book
on "What You Can Do with Your ATARI." Rather, it is a book
on how to use BASIC with an ATARI. While many of the special
ATARI features are included, they are used only as illustrations
or applications of BASIC words.

Each activity is presented as a "Problem" in a workbook.
Children will find the problems both interesting and geared to
their level of understanding. They will feel satisfaction in being
able to fill in the blanks in the workbook. As the book is
completed, a stock of successful programs is accumulated.
Frequently a child will spend long periods of time repeating and
varying a single activity.

As a child progresses through the workbook, she/he will learn
how to use many features of BASIC. Because the commands
have been made meaningful, the children will have established
a firm base of knowledge. As they grow older, they will be able to
extend their knowledge and apply it to more difficult, and more
"mathematical" problems.

Overview

Children are able to mimic before they can create. In some of
the problems they are directed to run sample programs, then
modify them. In others, the children are to complete partially
written programs.

Most young children will need a HELPER available (parent,
teacher, older child). The helper should read the COMMENTS
AND DESCRIPTIONS section to see what is required, and what
explanations are suggested. Older children may need occasional
assistance.

The BASIC vocabulary of each group of problems is given below.
See the COMMENTS AND DESCRIPTIONS section for more
details.

roup

Problems

BASIC Vocabulary

1-5

PRINT, GOTO, END

6-7

INPUT, DIM A$(20)

9-15

FOR . . . NEXT

16-20

IF . . . THEN

21-24

POKE, PEEK

25-28

A$(3), A$(l,3), LEN(A$)

29-32

arithmetic operations

33-34

SOUND, STEP-1

35-40

RND(l)

Comments and Descriptions
Problems 1-5

The first problems teach the words PRINT and GOTO, as well as
the purpose of line numbers.

1. SEASON'S GREETINGS. The program prints an endless
number of greetings. To stop it, press the BREAK key. PRINT
by itself makes the computer skip a line.

2. TAKE A NUMBER, PLEASE. The line numbers attached to
each statement determine the order in which the computer
goes through the program. Even if the lines are entered in
mixed-up order, the computer knows which should come next.
Type LIST to see the lines in their correct order.

3. MISTAKES. Every time RETURN is pressed, the ATARI
checks the line. If it finds a mistake, it prints an error message.
However, your mistakes might make sense to the computer. In
that case you'll find something wrong when you try to run the
program. If the computer prints a (zero) where you expected a
word, you probably forgot the quotation marks.

4. INITIALS. The example makes a large P from small ones. To
design a slanted initial, like A or W, it may be helpful to use a
grid.

5. WHERE NOW?. A puzzle which emphasizes that the
computer will always go to the next higher line number if it
isn't told to go somewhere else. END is necessary to stop the
program without printing extra letters. A semicolon at the end
of a PRINT statement keeps the letters all printed on the same
row.

Problems 6 — 7

Most children have seen a computer ask "what's your name?".
The INPUT statement makes the computer stop until a word is
typed and RETURN pressed. The ATARI must know ahead of
time how many letters each word is allowed to have. DIM A$(20)
says that the word A$ will have no more than 20 letters.

6. WALLPAPER. The notation (a) means hold down the CTRL
key while typing the A key. The computer prepares a "box"
labeled P$. When the pattern is entered, the computer stores it
in the box. Every time the program needs the pattern, it goes to
the box and looks inside. (Demonstrate with a labeled box and
a piece of paper with a pattern on it. )

7. LETTER TO SANTA. (Young children will object on the
grounds that they're too old for this.) Four words are used in
this program. A matching exercise has the child connect the
name on each "box" with what it contains.

Problems 8- 15

The next group is based on the FOR . . . NEXT instructions. The
first instance of FOR . . . NEXT is to make the computer pause.
In other applications it does something each time it counts.
Cursor controls are used in graphics applications of loops and
delays.

8. CURSOR CONTROLS. This problem shows how to make
your program clear the screen, move the cursor and print
reversed characters. E represents the ESC key.

9. PAUSING FOR BREATH. The computer prints a line, then
pauses while it counts to 5000, then prints another line. Use a
stopwatch or watch to time how fast it can count.

10. ROCKETS. The cursor controls, graphics characters and
the pause are combined to draw rockets shooting up into the
blue.

1 1 . COUNTING. Watch the computer while it counts. How
much longer does it take to count to 5000 when the numbers
are printed? Finally, a reaction test checks on your reflexes.

12. TOUCH YOUR TOES Make the computer repeat an

action while it counts. It can print a message, skip lines or
draw the sides of a box.

13. MOVERS. A double application of FOR . . . NEXT. One FOR
. . . NEXT is used to repeat the printing of the star; the other is
used to slow down the printing. Movement is really an illusion.
If a star is printed, erased and printed again one space further
along, it will appear to move.

14. THE WORM. The same as #13, but this time a worm
crawls across the screen. To erase the tail, it's necessary to
back up six spaces.

15. MORE COUNTING. A review of FOR. . . NEXT. This time the
upper limit is an INPUT. It's not necessary to prepare a special
box for numbers; the computer does that automatically.

Problems 16-20

These problems introduce the idea of testing, i.e., comparing
two things. Testing is done with IF something is true THEN do
something. The equals sign, = , means "is the same as"; the
"<>" means "is not the same as." Testing is done first with
words, then with numbers.

16. TESTING. Simple and complicated statements can be
tested. IF A$ = "RED" OR A$ = "BLUE" is an example. THEN is
followed by an action, in this case PRINT.

17. GOLDILOCKS. Complete the program by testing the
temperature of the porridge.

18. ANIMAL GUESS. This program uses IF. . .THEN with
branching. Younger children will probably be content with
changing line 100 every time. Others may want to make this a
two-person game.

19. LITTLE INDIANS. A short program combines FOR. . . NEXT
with IF. . .THEN to print out the counting rhyme. This is more
complicated than it appears as the child must supply the upper
limit, the test and the final message.

20. NURSERY RHYME. The problem is to write a program
which prints out a rhyme like that in #19.

Problems 21—24

These problems use POKE, PEEK and SETCOLOR. PEEK is
used to look at what's in a certain memory location. POKE is
used to change what's in the location. SETCOLOR is used to
change the color of the screen, the border and the letters. The
locations contain information about the color of the screen, the
color of the border, the presence or absence of the cursor and
the name of the last key touched. All this information is in
special codes.

21 . BLINKING LIZARDS. Make the orphan blink her eyes. To
make only the eyes change, we move the cursor and print on
top of them. POS.2,0 puts the cursor back in the upper left
corner. POKE 752, 1 will make the cursor disappear.

22. SCREEN COLORS. Experiment with different colors for the
screen and border by using SETCOLOR.

23. PEEKABOO. While a program is running, the computer
constantly checks the keyboard to see what key is being
pressed. If it's the BREAK key, the program will stop. Each time
a new key is pressed, the code number for that key goes into
location 764. To learn the code numbers for the keys, PEEK
into 764. Even though we take our hands away, the number in
764 doesn't change until a different key is pressed.

24. FUNNYBONES. . . . Use the code numbers found in #23 to
make the computer respond differently to certain keys.

Problems 25 - 28

These problems are concerned with words and parts of words.
A$(3) and A$(l,3) are denned, as well as LEN(A$).

25. QUIZ TIME. While no new BASIC concepts are introduced,
this is more complicated than any of the earlier programs. All
the answers are stored in the A$ box. Answers are checked;
sometimes a wrong answer produces another chance.

26. PIECES OF WORDS. An investigation into A$(3), A$(l,3),
LEN(A$), etc. Attention is restricted to the first N letters of a
word, or all but the first N letters.

27. RHYMING GAME. The string functions A$( 1 , 1 ) and
LEN(A$) are used to give hints to the guesser. Children will
enjoy thinking of tricky rhymes that aren't given away by the
two hints.

28. WORD PUZZLE. Using the beginnings and endings of a
word, print out other words. This should be done with a pencil
and then checked.

Problems 29 - 32

Very simple arithmetic operations on variables are introduced
in these problems. Experience has shown that manipulating
variables generally requires a high level of mental development
and the ability to handle abstractions. The operations in these
problems are kept as concrete as possible.

29. DOING MATH. The operation is doubling. The * is the
multiplication sign on the computer. Change the operation to
tripling. Have older children change the program to dividing by
2, doubling and adding 3, etc.

30. MATH QUIZ. Two values are input. The user is asked to
add them; the computer checks the answer. An extension
would be to have a wrong answer cause the problem to be
printed again. All children can change this to a multiplication
quiz.

31. TIMES TABLES. First the computer prints multiples of 2.
Then labels are added so that the output looks like a
multiplication table. Younger children may have difficulty
understanding the elaborate PRINT statement, but they will be
delighted with the output and will be able to change it.

32. DAYS AND NIGHTS. Use the computer to solve the problem
of how much we sleep in a year if we sleep eight hours a night.
Several variables are used, but their names are highly
mnemonic.

Problems 33 — 34

SOUND and more complicated FOR . . . NEXT loops are
demonstrated in these problems. SOUND is limited to varying
the pitch; volume can be adjusted on the TV set. STEP — 1 is
used to count backwards.

33. SOUNDING OFF. After experimenting with single notes, a
FOR N = 10 TO 40 loop produces a downhill sequence. Finally,
the keyboard codes are used to generate notes. Try typing
various words to see how they sound. Slow typists should
increase the 50 in line 10.

34. COUNTDOWN. Simple demonstrations of how to count
from 5 down to 1 . Two FOR. . . NEXT loops will let you count up
and then down again.

Problems 35 - 40

The last six problems all require the computer to "think" of a
number. This is done by using the random function RND( 1).
The expression

INT(RND(1)*6+1 )
must be used to obtain an integer from 1 to 6.
Older (10 and up) children may understand the explanation:

R N D ( 1 ) is a (decimal) number between and 1

RND(1)*B is a (decimal) number between and 6

RND(1)*G+1 is a (decimal) number between 1 and 7

INT means take the whole number part, so

INK RND ( 1 ) *G+ 1 ) is one of: 1,2,3,4,5,6

35. THINK OF A NUMBER. How to use the formula to roll a die.
The results of six rolls are recorded.

36. TWO DICE. Every time the computer has to think of a
number from 1 to 6, the expression INT(RND(1)*6 + 1) must be
used. The lines of this program are used in the next problem,
so don't NEW it.

37. GET OUT OF JAIL. The classical reason for rolling two
dice. The program uses FOR. . .NEXT for the three rolls,

IF. . .THEN for the test. Remind the child that " = " means "is
the same as."

38. NUMBER GUESS. The computer thinks of a number and
the user tries to guess it. Messages of TOO BIG and TOO
SMALL are printed. A counter is added to count how many
guesses are used. Compare it with the highway counters: every
time a car drives over it, it increases the counter.

39. ANSWER MACHINE. Like a crystal ball, the computer can
see into the future. After being asked a question, the computer
randomly selects one of its supply of answers.

40. SOUND AND LIGHT SHOW. The grande finale! When
completed, this program will play random notes while flashing
random screen colors; the rhythm is also random. A
spectacular finish to the problems.

PROBLEM 1 SEASON'S GREETINGS

A. Enter this program — that means after typing each line, you
press RETURN — and RUN it.

10 PRINT "HAPPY"

20 PRINT "THANKSGIVING"

Copy what happened

B. Enter two more lines:

30 PRINT
40 GOTO 10

and RUN the program again. To stop it, press the BREAK key.

What happened this time?

What did line 30 do? (If you're not sure, type 30 and press
RETURN to erase it; then run the program again and see what's
different.)

C. Enter NEW to erase this program. Now you write a program
that prints

BE MY
VALENTINE

e t c ♦

Copy your program here:

D. Enter NEW. Write a program that prints

LITTLE BOPEEP
LOST HER SHEEP

BOOHOO

Copy your program here:

Be sure your program skips a line before BOOHOO.
Add line 50 so that BOOHOO keeps repeating:

PROBLEM 2 TAKE A NUMBER, PLEASE

Enter and run each program. Copy the output (what the
computer prints on the screen) for each one.

A. NEW

38 PRINT "SUE HAS A"
57 PRINT "BIKE"
73 PRINT "LIGHT"

Output

B. NEW

86 PRINT "SAM HAS A"
93 PRINT "BIKE"
88 PRINT "LIGHT"

Output

Why did the programs print something different?

PROBLEM 3 MISTAKES

When a program line is entered, the ATARI checks it for
mistakes. It will refuse to accept the line for lots of reasons:

misspellings

lower case letters

reverse (blue on white) letters

no line number

Sometimes, however, the line will pass the check, but it won't
be right.

Enter this program and run it:

10 PRINT "RED"
20 PRINT "HOT"
30 PRINT PEPPER

What was printed?

■mHHH

Change line 30 so that the program prints

RED
HOT
PEPPER

Write your new line 30 here

PROBLEM 4 INITIALS

Run this one:

10
20
30
40
50
60
70
80

PRINT
PRINT
PRINT
PRINT
PRINT
PRINT
PRINT
PRINT

II D D B D !l
II □ p II

"PPPP"
II p II

II p II

Write a program like this that uses your initial; it should make
a large initial out of several small ones.

Copy your program here: (you might not need all the lines)
10

PROBLEM 5 WHERE NOW?

Unless you tell it to go somewhere else, a program that just
finished one line will go to the next line number.

A. Look at this program. PREDICT what it will do. Then enter
and run it to check.

10 GOTO 35
15 PRINT "T" 5
20 GOTO 45
25 PRINT "A" 5
30 GOTO 15
35 PRINT "R" 5
40 GOTO 25
45 END

Prediction:

B. Fill in the GOTO statements to make the program print ART.

10 GOTO ♦ ♦ ♦ ♦
15 PRINT "T"

20 GOTO ♦ ♦ ♦ ♦
25 PRINT "A"

30 GOTO

35 PRINT "R"?

40 GOTO

45 END

What makes the letters print on the same line?
C. Complete this program so it prints MICE

10 GOTO ♦ . . .

20 PRINT "E"

30 GOTO

40 PRINT "I"

50 GOTO

G0 PRINT "M"

70 GOTO . . ♦ .
80 PRINT "C"

90 GOTO ♦

100 END

PROBLEM 6 WALLPAPER

This program will design wallpaper. You'll give it a basic
pattern, and it will keep repeating it.

Each time it's run, the program will ask for the pattern. When
it does, type in a pattern and press RETURN.

The computer will put the pattern in a special place, called P$.
Line 10 tells the computer that the pattern won't be more than
20 characters long.

10 DIM P$(20)

20 PRINT "WHAT'S THE PATTERN"

30 INPUT P$

40 PRINT P$5

50 GOTO 40

Press the BREAK key to stop the program.

We'll use the graphice characters for the patterns.

HOLD DOWN THE CONTROL KEY WHEN YOU TELL
THE COMPUTER THE PATTERN!

Try these:

I j The circles mean hold down CTRL.

You can use the ATARI key to reverse the pattern.

6. ®....A®

Press the BREAK key to stop the program

PROBLEM 7 LETTER TO SANTA

In this program, the "user" (that's whoever is running it) will
enter four pieces of information. Lines 11, 12, 13 and 14 put
names on special places for the four different things.

Read through lines 1 1 — 90. Then answer the questions at the
end.

11 DIM N$(20>

12 DIM G$(20)

13 DIM Q$(20)

14 DIM QG$(20

20 PRINT "WHAT'S YOUR NAME"

30 INPUT N$

40 PRINT "WHAT WOULD YOU LIKE?"

50 INPUT G$

60 PRINT "WHO ELSE IS ON YOUR LIST?"

70 INPUT 0$

80 PRINT "WHAT WOULD "5 Q$ 5 " LIKE?"

90 INPUT QG$

100 PRINT

110 PRINT "DEAR SANTA"

120 PRINT "PLEASE BRING ME "5

130 PRINT

140
150

1G0
170

PRINT
PRINT
PRINT
PRINT

WOULD
THANK

LOVE"

LIKE A
YOLK"

" ;

180 PRINT

Draw a line from each "name" to what it stands for.

gift you'd like

other person's name

other person's gift

QG$

your name

the "

names"

should he written in each set of

in the
program.

Put in the names and run the program to check it.

PROBLEM 8 CURSOR CONTROLS

On the ATARI computers you can move the cursor up, down,
right and left by using the cursor control keys.

To control the cursor, hold down the control key, CTRL, while
pressing the arrow key.

You can clear the screen by holding down CTRL and pressing
CLEAR.

You can switch to reversed characters by using the ATARI key.
Switch back by pressing it again.

If these commands are inside a PRINT statement, your program
will make the cursor move and the screen clear.

To clear the screen or command the cursor inside a PRINT
statement, you MUST hit the ESCAPE key first. Whenever you
see E, hit the ESC key. Whenever a key is circled, hold down
the CTRL key while you hit it.

Type in this program, but don't run it yet:

10 PRINT " E (cle ar^ HELLO " Cg 1 e aj9 mea ns hold

CTRL and hit

CLEAR

20 PRINT "E \ THERE! "

On the screen you should see

10 PRINT " 3 HELLO"
20 PRINT " I THERE! "

The ATARI key does not need the ESC key.

Add these lines to your program and run it:

</k HOW ARE-/K YOU?"
HE | HE \ XE \ XE \ HE\^~HE\*

30 PRINT
^0 PRINT

What did line 40 draw?

For the rest of this book, when you see

PRINT " D "
you should really type

(clear)

where clear means
hold CTRL and hit
CLEAR.

EHi^n^HaRii

PROBLEM 9 PAUSING FOR BREATH

To slow down the computer, we can make it stop and count to
itself. Since it counts very fast, we'll have to make it count to a
high number.

To see how to do it, enter and run this program

10 PRINT " ONE MINUTE t

20 FOR T = 1 TO 5000

30 NEXT T

40 PRINT

50 PRINT "NOW WHAT?"

Get a watch or stopwatch and time how long it takes from the
time you press RETURN after typing RUN until the NOW
WHAT? appears. Then change the 5000 in line 20 to each of the
following numbers and time the delay.

5000.

.sec

10000

40000

PROBLEM 10 ROCKETS

We're going to send rockets up into the wild blue yonder. The
rocket body will be made with reversed characters.

10 PRINT"

20 PRINT" JJ^ U* J^ "

30 PRINT" J\\^ S* J\{ "

40 PRINT" J|k, A* JK "

50 PRINT" CjLX^L^ "

Run this to check how your rocket looks. When it's OK, add
these lines:

70
71
72
73
74
75
33

PRINT
PRINT
PRINT
PRINT
PRINT
PRINT
GOTO 10

Run the program. The rockets should be zooming up. Add more
PRINT statements before line 99 if you think the rockets should
be farther apart.

To make the rockets blast off, add a pause at lines 55 and 56:

55 FOR T = 1 TO 2000
5G NEXT T

Adjust the pause, if you like.

Now for some exhaust at ignition time. After the pause we'll put
in some smoke:

G0 PRINT "XX"
61 PRINT "YY"

PROBLEM 1 1 COUNTING

To watch the computer count, enter this program and run it:

10 FOR K = 1 TO 15
20 PRINT K
30 NEXT K

Change line 10 so the numbers from 1 to 100 appear:

Change line 20 so all 100 numbers are on the screen at one
time (like Wallpaper) :

Get out your watch and time how long it takes the computer to
count to 5000 if it has to take time to write the numbers. It
takes

sec

Run the next program three times to test your reflexes.

10 PRINT " 3) "

20 PRINT "WHEN THE NUMBERS APPEAR"

30 PRINT "PRESS THE BREAK KEY"

40 FOR T = 1 TO 1500

50 NEXT T

B0 FOR K = 1 TO 500

70 PRINT K

80 NEXT K

What were your reaction numbers?

How can you tell if someone presses BREAK before the numbers
appear?

PROBLEM 1 2 TOUCH YOUR TOES TEN TIMES

The FOR. . . NEXT loop (that's what it's called whenever you use
FOR and NEXT to count something) can be used to do
something a fixed number of times. Try each of these to see
how:

A. It can print a message.

10 FOR M = 1 TO 10
20 PRINT "TOO BAD"
30 NEXT M

Change line 20 to print something else.

B. It can skip spaces.

20
30
40
50
G0
70
80

PRINT
PRINT
PRINT
PRINT
FOR S =
PRINT
NEXT S
GOTO 10

"A"

I w »
A

II w II

II \./ II

1 TO 25

C. It can draw a box.

10 PRINT "###»#"

FOR S

1 TO 10

30 PRINT "#. ♦ ♦*"

40 NEXT S

50 PRINT "#####"

Erase the dots in line 30 so the box is empty.

Write a program that draws a high, wide box.

PROBLEM 13 MOVERS

Enter and run this program.

100 PRINT M D * M ;

110 FOR K = 1 TO 35

120 PRINT M * u 5

150 NEXT K

What happens?

If we erase each star before we print the next one, it will look as
if just one star is moving. Change line 120 so that it erases as it
goes:

120 PRINT

s p\ * - ,

Run it now. Does the last star stay or disappear?
Finally, make the star leave a trail of dots:

120 PRINT'E— * M 5

PROBLEM 14 THE WORM CROSSES

This time we'll move a worm. The worm will have five body
segments and a head.

The body segments are made by CTRL and T.

To erase the tip of the tail, we'll need to move back six times
and then print a space. The symbol Z\ means hit a
space. z *

1000 PRINT " (^

110 FOR K = 1 TO 30

120 PRINT "E — E -

130 FOR TO 50

140 NEXT T

150 NEXT K

Adjust the speed; make the worm cross more slowly, then make
it cross faster.

PROBLEM 15 MORE COUNTING

This program uses an INPUT statement, so the user can tell the
computer how high to count.

Because it's being told a NUMBER, not a WORD, the $ is not
used.

How High will be called HH in the program.

Enter and run this program:

10 PRINT "HOW HIGH SHOULD I COUNT?"

20 INPUT HH

30 FOR K = 1 TO HH

40 PRINT K

50 NEXT K

What happens when you answer the "HOW HIGH ..." question
with the word TEN?

(When the computer expects a NUMBER, you must enter a
number.)

Add a line to make the program print

ALL DONE

when it has finished counting. Write the line you added here:

What punctuation mark at the end of line 40 will make the
computer print the counting numbers across the

screen?

Try it.

PROBLEM 1 6 TESTING WITH IF...THEN

In BASIC, " = " means "is the same as"

"<>" means "is not the same as"

We can compare numbers and we can compare words.

Enter and run this program:

5 DIM C$(20)
10 PRINT "TELL ME A COLOR"
20 INPUT C$

30 IF C$ = "GREEN" THEN PRINT "GRASS IS
GREEN"

EISKI

What happens if you say RED?

Now you add line 40 so that the response to PINK is

VERY PREPPY*

Write line 40 here:

Finally, add line 50:

50 IF C$ = "RED" OR C$ = "BLUE" OR C$
"YELLOW" THEN PRINT "PRIMARY COLOR"

Run the program for all the colors you've used.

PROBLEM 17 GOLDILOCKS

Complete and enter the Goldilocks program:

3 DIM A* (20)

5 PRINT " O WHOSE PORRIDGE IS IT?"

10 PRINT "E t TASTE THE PORRIDGE"

15 PRINT "E I ENTER HOT* COLD* OR OK"

20 INPUT A$

30 IF A* = "HOT" THEN PRINT "PAPA'S"

40 IF A$ = "COLD" THEN PRINT "

60 END

PROBLEM IS ANIMAL GUESS

Now we'll use IF THEN to play a guessing game. First we'll

set the animal to be a HORSE, then well add extra lines to
make it a two-person game.

Look at the program. What happens after line 140 if the guess
is HORSE?

Complete line 170, then enter and run the program.

10 DIM AN* (20)
20 DIM G$(20)

100 AN$ = "HORSE"

110 PRINT O "

120 PRINT "I'M THINKING OF AN ANIMAL

130 PRINT "E \ GUESS"

140 INPUT G$

150 IF G$ <> AN$ THEN PRINT "NO"

1G0 IF G$ <> AN$ THEN GOTO 130

170

Once the program is working, add these lines:

10 PRINT "THINKER"

20 PRINT "TELL ME AN ANIMAL"

100 INPUT AN$

115 PRINT "GUESSER'S TURN"

The thinker types in an animal while the guesser isn't looking.
Then the guesser tries to guess it.

PROBLEM 19 LITTLE INDIANS

We're going to write a program that prints

1 LITTLE

2 LITTLE

3 LITTLE
INDIANS

4 LITTLE

5 LITTLE
G LITTLE

INDIANS

7 LITTLE

8 LITTLE

9 LITTLE
INDIANS

10 LITTLE
NAM A JO KIDS

Underneath which numbers is the word INDIANS?

Complete this program and run it.

10 FOR K = 1 TO

20 PRINT K5 " LITTLE"

30 IF K =

OR K

OR K =

THEN

40 NEXT K

PROBLEM 20 NURSERY RHYME

Now you write a counting rhyme program. Your program
should print one of the rhymes below.

1
2
3

5
ONCE I CAUGHT

10
THEN I LET IT

or this one

1
2
3

MARY AT THE COTTAGE DOOR

8
EATING CHERRIES OFF A PLATE

Use this space to record your program. You may not need all the
lines.

10 FOR

20 PRINT

30 IF

40 IF

50 NEXT

>> s

PROBLEM 2 1 BLINKING LIZARDS

When you want only part of a picture to move, then you have to
print on top of the picture.

Type in and run this program to draw part of a famous face.
The curls are made by using the symbol @ on top of the 8.

PRINT " t) " ;

PRINT " @@@ "

PRINT " @@@@@ "

PRINT " @ @"

PRINT " @0 0@"

FOR T = 1 TO 500

NEXT T

LIST the program. It will fit on the screen with the picture.

The eyes are in the 4th row of the screen. That's three rows
down from the top row. To get the cursor back to the upper left
hand corner, type this line:

80 POS*2»0
or, you can spell it out:

80 POSITION2»0
Move the cursor down three rows and close the eyes:

90 PRINT "f I E \ E I @- -@"

Run the program now.

To keep the eyes blinking, first put in a pause while they're
closed:

100
110

Send the cursor back to the beginning of the screen:

130 POS.2»0
and keep going:

140 GOTO 20

Run it now. Perfect, except for the cursor which keeps showing
right below your masterpiece.

To get rid of the cursor, use the line:

5 POKE 752>i

To get it back, you'll have to press the

SYSTEM
RESET

key after

you BREAK to stop the program.

Now change the eyes so that she winks instead of blinks.

PROBLEM 22 SCREEN COLORS

The ATARI has 16 different basic colors for the screen. Each
color has a code number. The darkest grey (it's almost black)
has code number . The code for a cherry-red is 4. Every
number from to 15 is a color code

The ATARI has special BASIC commands to change the color of
the screen and border:

SETCOLOR 4 changes the color of the border
SETCOLOR 2 changes the color of the screen.

Enter this program and run it to learn about
SETCOLOR.

100 PRINT "SCREEN COLOR?"

110 INPUT S

120 SETCOLOR 2tSt0

130 PRINT "BORDER?"

140 INPUT B

150 SETCOLOR 4>B»0

1G0 GOTO 200

What color does each color code make on your television
screen?

Code Number Color Code Number Color

2 10

3 11

4 12

5 13

6 14

7 15

PROBLEM 23 PEEKABOO — THE COMPUTER IS

WATCHING YOU

Even while it's running a program, the computer knows if
you've pressed a key, and it knows which key was the last one
touched.

Every key has a code number. The computer keeps the code
number of the last key pressed in memory location 764. To
learn some of the code numbers, well peek into location 764.

Enter this program:

10 K = PEEK(7Ba)
20 PRINT K
30 GOTO 10

Run the program and press different keys while the numbers
are running. The numbers will change each time you press a
different key. Find the code numbers for these keys:

space bar

RETURN

What happens when you touch the BREAK key?
Which black keys don't change the numbers?

PROBLEM 24 FUNNYBONES AND SORE TOES

Try this one. In line 30 use the code number for C.

10 PRINT "IF YOU TOUCH THE C"
20 PRINT "I 'LL SCREAM"

30 IF PEEK(7B4)
"EEEK ! "
40 GOTO 30

THEN PRINT

Change the scream to a call for HELP.

Give the computer a "funny key"; make it giggle when its funny
key is touched. You select the key and use its code number in
line 30. Write your funny-key program here.

Give the computer a sore key too. Make it say OUCH when the
sore key is pressed. Use line 35 for the sore-key test.

PROBLEM 25 QUIZ TIME

Read the program. How many questions are on the
quiz?

Complete line 90 so that the color question is asked again, if
the answer is not GREEN.

Then make up the last question on the quiz; use lines 120 —
150.

10 DIM A$<40>

20 PRINT " ^ QUIZ TIME"

30 PRINT

40 PRINT "WHAT IS THE CAPITAL OF

MICHIGAN?"

50 INPUT A$

G0 IF A$ = "LANSING" THEN PRINT "RIGHT"

70 IF A$ <> "LANSING" THEN PRINT "NO,

LANSING"

80 PRINT "WHAT DO BLUE AND YELLOW MAKE?"

90 INPUT A$

100 IF A$ = "GREEN" THEN PRINT "GOOD"

110 IF A$ <> "GREEN" THEN PRINT "TRY

AGAIN": GOTO

120 PRINT —

130 INPUT A$

140 IF A$ =

150 IF A$ <>

Have a friend try your quiz. Add another question if you like

PROBLEM 26 PIECES OF WORDS

Run this program. Copy the output, then try to answer the
questions.

5 DIM A$(20>

10 A$ = "BICYCLE"

20 PRINT A$(l>

30 PRINT A$(2)

40 PRINT A$(3)

50 PRINT

S0 PRINT A$( 1 »1 )

70 PRINT A$< 1 t2)

80 PRINT A$( 1 »3)

90 PRINT

100 PRINT LEN(A$)

Now suppose line 10 were changed to

10 A$

Predict what the output would be
Then check it.

MISSISSIPPI"

PROBLEM 27 RHYMING GAME

This program is a guess-the-rhyme game. The player gets three
guesses. Each time the guess is wrong, a hint is given.

Complete the missing lines. The first hint should be the first
letter of the secret word. The second hint should be the number
of letters.

10 DIM A$<20> * B$(20) i C$(20)

20 A$ = "RED"

30 B$ = "THREAD"

100 PRINT "O I'M THINKING OF A WORD"

110 PRINT "IT RHYMES WITH "JA$

120 PRINT "GUESS"

130 INPUT G$

140 IF G$ = B$ THEN GOTO 500

150 PRINT "NO. IT STARTS WITH "5

220 PRINT "GUESS"

230

240 IF

250

320 PRINT "LAST GUESS"

330

340

350 PRINT "NO t IT WAS " 5

3G0 END

500 PRINT

When the program is working, change A$ and B$ and let a
friend try your game.

PROBLEM 28 WORD PUZZLES

Look at this program. PREDICT the output. Then check it, by
entering and running the program.

10 DIM A$<20) * B$<20)

20 A$ = "STAY"

30 B$ = "RED"

40 PRINT A$(l t3) 5B$<1 ,1)

50 PRINT B$(l »1) !A$(3) #A$(1 »1)

Prediction

Now change A$ to "STRAWBERRY"
change B$ to "SHORTCAKE"

Change lines 40 and 50 so that the output is

BERRY
SHAKES

40
50

PROBLEM 29 DOING MATH

Enter and run this program:

10 PRINT "TELL ME A NUMBER"

20 PRINT "AND I'LL DOUBLE IT'

30 INPUT N

40 PRINT 2*N

Check that the computer can double these numbers:

-5

Make the computer triple the number. Try it out on some
numbers and write down the results.

(If you tried an enormous number, such as

10000000000
your answer came in "Scientific Notation."

2E + 10 means a 2 with 10 zeros after it.)

PROBLEM 30 MATH TEST

Math quiz time. Run this addition quiz.

10 PRINT O MATH TEST"

20 PRINT

30 PRINT "TELL ME A NUMBER"

a® INPUT A

50 PRINT "ANOTHER NUMBER"

60 INPUT B

70 PRINT

80 PRINT "WHAT IS"

90 PRINT A5 "+" !B

100 INPUT C

110 IF C = A+B THEN PRINT "RIGHT"

120 IF C <> A+B THEN PRINT "WRONG"

Change this to a multiplication test.

What lines need to be changed?

Make sure your changes are working

PROBLEM 3 1 TIMES TABLES

This time well make the computer multiply the first ten
counting numbers by 2.

Enter and run this program:

10 PRINT O TIMES TABLES"

20 FOR N = 1 TO 10

30 PRINT N» 2*N

40 NEXT N

We can make the output look like a math book,

2x1=2
2x2 = 4
2x3 = 6

by changing line 30. We want "2 x" and " = " to be printed each
time. Change line 30 to

30 PRINT "2 x "5 N5 " = " 5 2*N

and run the program.

Now change line 30 so the computer does the SEVEN'S table:

Make another change to do the TWELVE'S table. How much is
12 x 9?

PROBLEM 32 DAYS AND NIGHTS

If you spend two hours a day watching television, how many
24-hour days is that equal to?

If you sleep eight hours a night, how much sleep is that each
year?

The computer can be taught to solve problems like these.

Read this program.

50 DIM A$<40>
100 PRINT " O "

110 PRINT "WHAT'S THE ACTIVITY?"
120 INPUT A$

130 PRINT "|TELL ME HOW MANY HOURS YOU
SPEND EACH DAY"
140 PRINT A$
150 INPUT H
160 HY = H*3G5
170 PRINT "TOTAL HOURS " 5HY
180 CD = HY/24
190 PRINT "COMPLETE DAYS "5CD

There are four variables in this program. Match their names
with what they stand for:

hours each day
hours each year
the activity

total days and nights

Run the program for activities you do such as:

Playing the piano

Watching television

Sleeping

Reading

Looking for your socks

What things do YOU spend more than seven days each year doing?

How do you convert 14 days to two weeks?

Try to add two lines to the program to change CD, the number of
complete days, to CW, the number of weeks.

200

210

PROBLEM 33 SOUNDING OFF

The way to turn OFF the sound is to use END. END can be in
your program, or you can type it directly and press RETURN.

On the ATARI, there is a BASIC command called SOUND. This
program will make a single, short sound:

10 PRINT "ENTER NOTE NUMBER"

20 INPUT N

30 SOUND tU >10 »10

40 FOR K = 1 TO 100

50 NEXT K

S0 END

Run the program a few times. Each time give it a number
between and 255. A 72 should match the A above middle C on
the piano.

As the numbers get larger, do the notes get higher or lower?

100

Once a note starts, it keeps playing until either:
the program comes to another SOUND, or
the program comes to an END.

Here's how to change the program so you can enter four notes

10 FOR Z = 1 TO a

20 INPUT N

30 SOUND 0»N»10» 10

40 FOR K = TO 100

50 NEXT K

55 NEXT Z

60 END

Try these notes: 72, 108, 85, 164 (Press RETURN after each
number. )

Try other sequences; change line 10 for more notes.

To make "automatic" music, we can use a special FOR.
loop.

10 FOR N = 10 TO 40

20 SOUND 0»N»10»10

30 FOR K = 1 TO 100

40 NEXT K

50 NEXT N

60 END

Try changing the 100 in line 30, first to make the sounds
shorter, then longer. You can change the numbers in line 10,
too.

The keyboard code numbers can be used to make some weird
music. Enter this program:

10 FOR N = 1 TO 50

20 N = PEEK<7G4>

30 SOUND 0»N»10»10

40 FOR K = 1 TO 100

50 NEXT K

60 NEXT N

70 END

Type different letters while this is running. For color, add the
line

25 SETCOLOR 2 »N »0

The faster you type, the more notes you'll hear. See what your
name sounds like.

102

103

PROBLEM 34 COUNTDOWN

The computer can count backwards if you tell it to go
backwards. Try this program:

100 FOR K = 5 TO 1 STEP
110 PRINT K
120 NEXT K

Write a program that will print:

10
9

BLASTOFF!

104

Copy your program here.

Write a program that counts from 1 to 4 and then back down
to 1, like this:

1
2
3
4
3
2
1

106

PROBLEM 35 THINK OF A NUMBER

There's a special expression to make the computer "think" of a

number.

If you want X then let

to be one of X =

1, 2, 3 INT(RND(1)*3+1)

1,2,3,4,5,6 INT(RND(1)*6+1)

1,2 ,10 INT(RND(1)*10+1)

1,2,...., 100 INT(RND(1)* 100+1)

To roll a die, you want the computer to think of a number from
1 to 6. Here's how to do it:

20 D = INT(RND< 1 >*6+l )

30 PRINT "YOU ROLLED A " 5D

108

Either run this program six times or add lines 15 and 35 to
make a FOR. . . NEXT loop to repeat the roll:

15 FOR

35 NEXT

Record your rolls here:

PROBLEM 36 TWO DICE

This time we want to roll TWO dice. Each time we roll a die, we
must use

INT(RND(i)*G+l )

Enter this program. Either run it six times or put in a
FOR.... NEXT loop.

20 D = INT(RND( 1 )*6+l )
30 E = INT(RND(1)*G+1)
40 PRINT D >E

Roll the dice six times and copy your results:

111

PROBLEM 37 GET OUT OF (AIL FREE

Finish this get-out-of-j ail-free program and enter it. You may
use lines 20 — 40 of the last problem.

15 FOR R =

20 D = INT(RND(1)*B+1)
30 E = INT(RND(1 >*6+l )
40 PRINT D»E

50 IF

60 NEXT R

70 PRINT "SORRY* PAY $50."

80 END

100 PRINT "GET OUT OF JAIL FREE!"

112

Run this program six times. How many times did you get out of

jail free?

How many times did you pay $50?

113

PROBLEM 38 NUMBER GUESS

In this program, the computer "thinks" of a number and you
try to guess it. If you guess wrong, it tells you TOO BIG or TOO
SMALL. Complete the program and run it to check it out.

20 N = INT(RND(1)*100+1)

30 PRINT "I'M THINKING OF A NUMBER"

40 PRINT "GUESS"

50 INPUT G

70 IF G = N THEN 500

80 IF G < N THEN PRINT

90 IF G > N

100 GOTO

500 PRINT

114

What numbers did the computer think of?

What's the biggest number it's allowed to think of?

To count the guesses, add these lines:

5 C =

G0 C = C + 1

510 PRINT "IT TOOK YOU"

520 PRINT C5 " GUESSES"

Run the program several times and keep track of how many
guesses it took you.

115

PROBLEM 39 THE ANSWER MACHINE

Is it going to rain tomorrow? Will I find my watch under the
bed? Will my loose tooth come out today? Ask the computer

Well make up 10 answers and let the computer choose one
each time a question is asked.

Finish the program and run it:

PLEASE"

V ES"

10 DIM Q$<50)

20 PRINT "QUESTION*

30 INPUT Q$

40 PRINT

50 PRINT "THE ANSWER IS"

60 N = INT(RND< 1)*10+1 )

70 IF N = 1 THEN PRINT " t

71 IF N = 2 THEN PRINT "NO"

72 IF N = 3 THEN PRINT "WHEN

73
74
75
76

DONKEYS FLY"

116

90 GOTO 20

Put in a pause between lines 50 and 60 to make it look as
though the computer is thinking about the problem:

117

Use lines 81 - 85 to add five more answers. Change line 60 so
that the computer will think of a number from 1 to 15.

118

PROBLEM 40 SOUND AND LIGHT SHOW

This is the last problem; it's the grand finale. The computer will
"think" of a number from 1 to 255, play the note and color the
screen. Start with a program that plays a 50 note piece.

10 FOR N = 1 TO 50

20 V = INT(RND<1)*255+1)

30 SETC0L0R 2 *V >0

40 SOUND 0,U, 10,10

50 FOR K = 1 TO 100

60 NEXT K

70 NEXT N

80 END

This produces some wild music, but all the notes have the same
length. To have some notes long and some notes short, well let
the computer think of a number for the duration, D:

45 D = INT(RND(1>*255+1)
50 FOR K = 1 TO D

Happy listening and happy computing!

120

GLOSSARY

PRINT "HELLO" puts HELLO on the screen.

GOTO 50 sends computer to do line 50

next.

INPUT N program stops until the user

types a number and presses
RETURN.

INPUT A$ program stops until the user

types a word and presses
RETURN.

DIM A $ ( 2 ) there will be a word named A$

in the program. It has at most
20 letters.

FOR K = 1 TO 5 computer counts to 5 by itself.

NEXT K

FOR K = 1 TO 5 prints "HELLO" five times.

PRINT "HELLO"
NEXT K

END program stops here .

122

IF A = G THEN, . .

IF A <> 6 THEN. ♦ ♦

IF A$ = "HORSE" THEN. ♦ ♦

IF A = 6 OR A = 7 THEN. . .

testing whether things are the
same or different.

SETCOLOR 2 >12»0

SETCOLOR 4>0,0»

POKE 752,1

changes screen to color 12.
changes border to color 0.
makes the cursor disappear.

v =

= PEEK(7G4)

FOR K = 5 TO 1 STEP -1
PRINT K
NEXT K

X is the code number of the
last key touched.

counts backwards and prints
5,4,3,2,1 in a column.

SOUND 0,72*10,10

plays note 72 until turned off.

P0S.2 ,0

sends cursor to upper left
corner.

X = INT(RND( 1 )*G+1 )

X is one of: 1, 2, 3, 4, 5, 6.

J~,

124 V.

OM^Kl

126

Mary Jean Winter is a professor of Mathematics at Michigan State University.
She has been actively involved in mathematics education (K- 12) for the last 8
years. She was formerly a numerical analyst in industry and academia. She is
the author of Chivalry, Great Adventure, Wordspot and Witchnumber,
published by Comm*Data; numerous articles on using calculators and com-
puters in the classroom, as well as calculator activities for Scott Foresman's
elementary series math text book. The author also teaches computing at MSU
Summer Computer Camps for children ages 10-16. She has a Ph.D. in
mathematics from Carnegie Mellon University and an A.B. in mathematics and
history from Vassar College.

127

COMPUT6R nCTIVITI€S FOR TH€ VOUNG CHILD

COMPUT6R PLF1VGROUND, by Mary Jean Winter, is based on a child's natural interest in words, games and
graphics, fl collection of BfiSIC computer activities for the fitari 400/800/1 200, this book is intended for children
in grades 2 through 6.

Cach activity is presented as a "Problem" in a workbook format. Children will find the problems interesting, fun
and geared to their level of understanding. They'll type in and run sample programs — learn how to modify
them — and complete partially written programs, everything is kept simple so the child learns the programming
process step-by-step.

fls the child progresses, he or she will learn how to use many of the features of BASIC— PRINT, GOTO, INPUT,
FOR . . . NEXT, IF . . . TH6N, POK€ and P€€K commands are a few. Working in this manner, the child will build up a
collection of programs which are understandable and entertaining.

COMPUTCR PIAVGROUND is illustrated with over 70 color cartoons and pictures to color. It's BASIC program-
ming playtime!

COMPUTCR PLAVGROUND is also available for the Commodore 64/VIC 20 and Apple II, 11+ and //e
computers.

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